Conventionally, examples of liquid applicators of this kind include those shown in FIGS. 26 and 27 and in FIG. 28.
In FIGS. 26 and 27, a main body 31 has an application element 32 at its front end and a rotary actuator 33 inserted into its rear opening. Rotary actuator 33 is configured of an outer cylindrical part 34 and an inner cylindrical part 35 inserted therein so as to be unrotatable. Outer cylindrical part 34 has a fitting projection 34a, which is mated with a fitting recess 31a in main body 31 so that outer cylindrical part 34 is able to rotate and will not fall off with respect to main body 31.
A screw rod 37 is inserted inside inner cylindrical part 35. A male thread 37a formed on the outer periphery of screw rod 37 is mated with a female thread 35a formed at the front end of inner cylindrical part 35 and fitted through an extraordinarily shaped fitting hole 31c in a partition wall 31b formed on the inner surface of main body 31. By this arrangement, screw rod 37 can move in the longitudinal direction but is not rotatable with respect to inner cylindrical part 35. Formed at the front end of outer cylindrical part 34 is a pawl 39 which resiliently engages ratchet teeth 38 formed on the inner surface of main body 31. This pawl 39 and ratchet teeth 38 constitute a ratchet mechanism 40. A piston 41 is inserted so as to move slidably with respect to the inner surface of main body 31 and is joined to the front end of screw rod 37, in front of partition wall 31b.
In the thus configured liquid applicator, outer cylindrical part 34 is adapted to be rotatable in only one direction with respect to main body 31, being limited by ratchet mechanism 40. As outer cylindrical part 34 is turned relative to main body 31, inner cylindrical part 35 rotates together with outer cylindrical part 34. Upon this, screw rod 37 is prohibited from rotating by fitting hole 31c, so that screw rod 37 and rotary actuator 33 rotate relatively from each other. Therefore, screw rod 37 moves forwards by virtue of its screw fitting with female thread 35a to thereby move piston 41 forwards.
As a result, an application liquid L stored in an application liquid reservoir 31A of main body 31 is pushed out by piston 41 so as to infiltrate the liquid into application element 32.
An applicator shown in FIG. 28 has an application element 52 at the front end of a cylindrical main body 51 while a piston 53 and pressing cylinder 54 are inserted into main body 51 from its rear end. Ribs 54a formed on the peripheral surface of pressing cylinder 54 are fitted in grooves 51a formed on the inner surface of main body 51 along its longitudinal direction so that they can move. Therefore, pressing cylinder 54 can move in the longitudinal direction relative to main body 51 with its rotation being prohibited. A cylindrical rotary actuator 55 is inserted at the rear end of main body 51. Rotary actuator 55 has an annular fitting projection 55a formed on the peripheral surface thereof, and this fits into annular fitting recess 51b formed on the inner surface of main body 51. This configuration permits rotary actuator 55 to slide and rotate relative to main body 51 and prevents it from being pulled out. Further, a rear portion 56b of a screw rod 56 having a male thread 56a formed thereon is inserted into rotary actuator 55 so that it cannot rotate. The part of screw rod 56 in front of rotary actuator 55 fits and engages a female thread 54b formed on the inner surface of pressing cylinder 54 so that it is inserted in pressing cylinder 54. Rotary actuator 55 has ratchet teeth 55b which engage ratchet groove 51c formed on the inner surface of main body 51. The engagement between ratchet teeth 55b and ratchet groove 51c constitutes a ratchet mechanism 57 for limiting the rotation of rotary actuator 55 to one direction.
In the thus configured applicator, with the rotation of rotary actuator 55, screw rod 56 rotates so that pressing cylinder 54 fitted on the screw rod moves forwards along grooves 51a. Therefore, piston 53 located at the front end moves forwards so as to push out a liquid paint L stored in main body 51 toward application element 52 so that the liquid infiltrates into application element 52 and can be used for application.
Also in this applicator, rotary actuator 55 is prohibited from rotating in the reverse direction by ratchet mechanism 57, so that pressing cylinder 54 and piston 53 can only move forwards.
In the above way, in the conventional liquid applicators, since the rotation of rotary actuator 33 or 55 is converted into a linear movement of piston 41 or 53 so as to supply liquid paint L, it is possible to finely adjust the supplying amount and hence facilitate the working of a simple and appropriate application.
However, each of the above liquid applicators has the following problem because rotary actuator 33 or 55 is arranged in such a fitted manner as to slide and rotate with respect to main body 31 or 51 and the fitted portion is configured of annular fitting projection 33a or 55a formed on rotary actuator 33 or 55 and annular fitting recess 31a or 51b formed on main body 31 or 51.
That is, it is preferred that the depth of fitting recess 31a or 51b and the projected amount of fitting projection 33a or 55a should be set as large as possible in order to prevent rotary actuator 33 or 55 from dropping off from main body 31 or 51. However, since main body 31 or 51 usually has a thin-wall structure with polypropyrene or other resins for the necessity of being light-weighted and of inexpensive configuration, it is difficult to configure fitting recess 31a or 51b to be deep enough as stated above and hence it is impossible to provide a strong enough fitted portion. So, as an applicator of this kind which is often carried around, the conventional configurations are insufficient in their strength.
Nevertheless, rotary actuators 33 and 55 usually have a relatively thick-wall configuration. So, when this rotary actuator 33 or 55 is formed with a fitting projection 33a or 55a having a large projected amount and main body 31 or 51 is formed with a deep fitting recess 31a or 51b, a firm fitting engagement between rotary actuator 33 or 55 and fitting projection 33a or 55a can be configured thus making it possible to enhance the fitting strength of rotary actuator 33 or 55. In this case, however, sink arises on the surface of rotary actuator 33 or 55 at the site where fitting projection 33a or 55a is formed so as to be thick, markedly degrading its appearance, thus giving rise to difficulties in putting this configuration into effect.
In the applicator shown in FIGS. 26 and 27, a partition wall is formed on the inner face in the central part of main body 22, rotary actuator 33, screw rod 37 and the like have to be inserted from the rear of main body 22 while piston 41 needs to be fitted from the front end of main body 31. Further, piston 41 and screw rod 37 should be inserted from the front and rear and be joined inside the main body. Thus, the conventional configuration has the problem of the assembly operation being complicated and difficult, resulting in poor productivity. Moreover, since piston 41 is inserted into main body 31, the inside diameter of main body 31 needs to be equal to the diameter of piston 41, so that the inside diameter of main body 31 depends on piston 41. That is, there is a problem in that the dimensions and shape of main body 31 are limited thereby.
The present invention has been devised in view of the above prior art problems, and it is therefore an object of the invention to provide a liquid applicator in which the main body and rotary actuator are firmly fitted to each other whilst being rotatable, providing a high enough strength and good appearance and which is simple in assembly as well as being excellent in design flexibility.